✅3.1.5.3 - Volcanic Hazards Flashcards Preview

AQA A Level Geography - PHYSICAL > ✅3.1.5.3 - Volcanic Hazards > Flashcards

Flashcards in ✅3.1.5.3 - Volcanic Hazards Deck (39)
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1

What are the characteristics of shield volcanoes?

Gentle slopes, wide base
Frequent eruptions, basic lava
High speed and low viscosity basaltic lava
Non-violent eruptions

2

Where are shield volcanoes found?

Constructive boundaries

3

What are the characteristics of composite volcanoes?

Steep sides, cone shape
High with narrow base
Explosive eruptions
Layers of alternating ash and lava
Secondary/parasitic cones

4

Where are composite volcanoes found?

Destructive boundaries

5

What type of lava is rich in silica?

Slow flowing, viscous lava

6

What is generally erupted from volcanoes at destructive margins?

Lava bombs, ash, dust

7

What are primary effects?

Occur immediately along with the event, as a result of it

8

What are secondary effects?

Direct consequence of the event but not immediate

9

What are lava flows?

Streams of molten rock that pour or ooze from an erupting vent

10

What are the two types of lava?

Pahoehoe and A'a

11

What are the characteristics of pahoehoe lava?

Smooth, billowy surface, relatively thin

12

What are the characteristics of A'a lava?

Rough, jagged surface and thick lava

13

When lava solidifies, what does it form?

Igneous rock

14

How are gases released from magma?

As it rises to the surface and pressure decreases, gases are given off from the liquid portion

15

What are the main gases that lead to acid rain?

Carbon Dioxide and Sulphur Dioxide

16

How can acid raid impact the environment?

Polluting waterways and soil, killing plants and trees, dissolving rock

17

What is ash made up of?

Fragments of pulverised rock, minerals and volcanic glass

18

How is ash formed?

When dissolved gases in magma expand and escape violently into the atmosphere in explosive eruptions

19

What impacts can ash have?

It can disrupt aviation, critical infrastructure eg electric power supply, and impact health

20

What is a pyroclastic flow?

A high density mix of hot lava blocks, pumice, ash and volcanic gas

21

How fast can pyroclastic flows move?

700km/h

22

How do pyroclastic flows form?

Form collapse of an eruption column, colapse of lava domes, or 'boiling over'

23

Why are pyroclastic flows considered the most dangerous of volcanic hazards?

Their speed makes them inescapable, and due to high temperatures, it is impossible to survive one

24

What is a lahar?

A moving mass of soils or mud made fluid by rain or snow moving down a steep slope

25

What are lahars triggered by?

Heavy rain or large amounts of ground water flowing through rocks as it causes the top layer of soil to be removed

26

What are tephras?

Rock fragments and particles thrown into the air by volcanic eruptions

27

How can tephra lead to a pyroclastic flow?

If the rock fragments are hot enough to fuse together

28

How can tephra cause a temperature drop?

If they reflect light and heat from the sun while in the atmosphere

29

What are nuees ardentes?

Clouds of gas ash and lava fragments ejected from the volcano

30

What can form part of a nuees ardentes?

Pyroclastic flow